<PAGE>
 
                                                                     EXHIBIT 4.6

     The following form of Common Stock Purchase Warrant was issued by the
Registrant to each of St. Paul Fire & Marine Insurance Company, SBIC Partners,
L.P., Brentwood Associates V. L.P., Bruce Hendry and Tonkawa N.G. Partners.
<PAGE>
 
THE SECURITIES EVIDENCED BY THIS WARRANT OR ISSUABLE UPON EXERCISE HEREOF HAVE
NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR
APPLICABLE BLUE SKY LAWS AND ARE SUBJECT TO CERTAIN INVESTMENT REPRESENTATIONS.
THESE SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE OR TRANSFERRED IN THE ABSENCE
OF AN EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT AND SUCH APPLICABLE BLUE
SKY LAWS OR AN EXEMPTION THEREFROM.



Warrant No. 96-_                                               December 16, 1996

                         COMMON STOCK PURCHASE WARRANT


          THIS CERTIFIES THAT, for value received, and permitted assigns
("Warrantholder"), is entitled to purchase from Plasma & Materials Technologies,
Inc., a California corporation (the "Company"), on the terms and conditions
contained herein, Forty-Nine Thousand and Twenty (49,020) shares of the
Company's Common Stock, no par value per share (the "Common Stock"), at a price
of Twelve Dollars and Seventy-Five Cents ($12.75) per share (the "Warrant
Price").

          1.   Exercisability of Warrant.  This Warrant shall be exercisable in
               -------------------------                                       
the following manner:  (a) fifty percent (50%) of the shares of Common Stock
subject hereto (the "Warrant Shares") shall be immediately exercisable and (b)
the remaining shares of Common Stock subject hereto (the "Remaining Warrant
Shares") shall be exercisable, if at all, following the funding by Warrantholder
of all or any portion of the amount that such Warrantholder has committed to
fund (the "Commitment") under that certain Note Purchase and Loan Agreement
dated as of an even date herewith (the "Note Purchase Agreement") among the
Company, Warrantholder and the other parties thereto.  Following each funding
under the Note Purchase Agreement, the Remaining Warrant Shares will become
exercisable in an amount equal to that number of shares determined by
multiplying the Remaining Warrant Shares by a fraction, the numerator of which
is the dollar amount actually funded at such time by Warrantholder under the
Note Purchase Agreement and the denominator of which is the Commitment.

          2.   Method of Exercise; Payment; Issuance of New Warrant; Transfer
               --------------------------------------------------------------
and Exchange.  This Warrant may be exercised by Warrantholder, in whole or in
------------                                                                 
part, by the surrender of this Warrant, properly endorsed, at the principal
office of the Company at 9255 Deering Avenue, Chatsworth, California 91311, and
by (a) the payment to the Company of the then applicable Warrant Price of the
Common Stock being purchased, which Warrant Price may be paid, in whole or in
part, by the delivery of cash, check and/or Notes (as defined in the Note
Purchase Agreement) in an amount equal to such Warrant Price, and (b) delivery
to the Company of a customary investment letter executed by Warrantholder,
confirming that the shares of Common Stock being purchased are being acquired
for Warrantholder's own account and not with a view to or for sale in connection
with any

                                      2.
<PAGE>
 
distribution of such shares, acknowledging securities law restrictions
applicable to such shares, and agreeing that certificates evidencing such shares
shall bear a legend accordingly restricting the transfer of such shares.  In the
event of any exercise of the rights represented by this Warrant, certificates
for the shares of Common Stock so purchased shall be delivered to Warrantholder
within a reasonable time after the rights represented by this Warrant shall have
been so exercised, and unless this Warrant has expired, a new Warrant
representing the number of shares of Common Stock, if any, with respect to which
this Warrant shall not then have been exercised or that may become exercisable
after such date, shall also be issued to Warrantholder within such time.  In
lieu of exercising this Warrant for a specified number of shares of Common Stock
(the "Exercised Shares") and paying the aggregate Warrant Price therefor (the
"Exercise Price"), Warrantholder may elect, at any time after the Exercise Date
and prior to the expiration of this Warrant, to receive a number of shares of
Common Stock equal to the number of Exercised Shares minus that number of shares
of Common Stock having an aggregate Fair Market Value equal to the Exercise
Price.  Following such election, the number of shares of Common Stock covered by
this Warrant shall be deemed automatically reduced by the number of Exercised
Shares.  For purposes of this Warrant, the "Fair Market Value" shall mean the
closing sales prices of Common Stock quoted on Nasdaq National Market or, if
then traded on a national securities exchange, the average closing prices of
Common Stock on the principal national securities exchange on which listed or,
if quoted on the Nasdaq over-the-counter system, the average of the mean of the
closing bid and asked prices of Common Stock quoted on such system, in any such
case on each of the ten (10) trading days immediately preceding the date of such
conversion.

          3.   Stock Fully Paid; Reservation of Shares.  The Company covenants
               ---------------------------------------                        
and agrees that all shares of Common Stock that may be issued upon the exercise
of the rights represented by this Warrant will, upon issuance, be fully paid and
nonassessable and free from all liens.  The Company covenants and agrees that,
during the period within which the rights represented by this Warrant may be
exercised, it shall reserve for the purpose of the issuance upon exercise of the
purchase rights evidenced by this Warrant, at least the maximum number of shares
of Common Stock as are issuable upon the exercise of the rights represented by
this Warrant.

          4.   Restrictions on Transferability of Securities; Compliance with
               --------------------------------------------------------------
Securities Act.
-------------- 

          (a)  Restrictions on Transferability.  This Warrant and the shares of
               -------------------------------                                 
Common Stock issuable hereunder shall not be transferable except upon the
conditions specified in this Section 4, which conditions are intended to insure
compliance with the provisions of the Securities Act of 1933, as amended (the
"Securities Act").  Each holder of this Warrant or the Common Stock issuable
hereunder will cause any proposed transferee of the Warrant or such Common Stock
to agree to take and hold such securities subject to the provisions and upon the
conditions specified in this Section.

                                       3.
<PAGE>
 
          (b) Restrictive Legend.  Each certificate representing (i) this
              ------------------                                         
Warrant, (ii) the shares of Common Stock issued upon exercise of the Warrant and
(iii) any other securities issued in respect of such shares of Common Stock upon
any stock split, stock dividend or similar event (collectively, the "Restricted
Securities"), shall (unless otherwise permitted by the provisions of Section
4(c) below or unless such securities have been registered under the Securities
Act) be imprinted with the following legend, in addition to any legend required
under applicable state securities laws:

          THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
          1933, AS AMENDED (THE "ACT"), OR APPLICABLE BLUE SKY LAWS, AND ARE
          SUBJECT TO CERTAIN INVESTMENT REPRESENTATIONS.  THESE SECURITIES MAY
          NOT BE SOLD, OFFERED FOR SALE OR TRANSFERRED IN THE ABSENCE OF AN
          EFFECTIVE REGISTRATION UNDER THE ACT AND SUCH APPLICABLE BLUE SKY LAWS
          OR AN EXEMPTION THEREFROM.

          Upon request of a holder of a certificate with such legend imprinted
thereon, the Company shall remove the foregoing legend therefrom or, if
appropriate, issue to such holder a new certificate therefor free of any
transfer legend, if, with such request, the Company shall have received either
the opinion referred to in Section 4(c)(i) or the "no-action" letter referred to
in Section 4(c)(ii) to the effect that any transfer by such holder of the
securities evidenced by such certificate will be exempt from the registration
and/or qualification requirements of, and that such legend is not required in
order to establish compliance with the Securities Act, and if applicable, any
state securities laws under which transfer restrictions on such securities had
been previously imposed.

          (c) Notice of Proposed Transfers.  The holder of each certificate
              ----------------------------                                 
representing Restricted Securities by acceptance thereof agrees to comply in all
respects with the provisions of this Section 4(c).  Prior to any proposed
transfer of any Restricted Securities, the holder thereof shall give written
notice to the Company of such holder's intention to effect such transfer.  Each
such notice shall describe the manner and circumstances of the proposed transfer
in sufficient detail, and shall be accompanied by either (i) an unqualified
written legal opinion addressed to the Company from counsel who shall be
reasonably satisfactory to such parties, which opinion shall be reasonably
satisfactory in form and substance to such parties' legal counsel, to the effect
that the proposed transfer of the Restricted Securities may be effected without
registration under the Securities Act and any applicable state securities laws,
or (ii) a "no-action" letter from the Securities and Exchange Commission (and
any necessary state securities administrator) to the effect that the transfer of
such securities without registration will not result in a recommendation by the
staff of the Commission (or such administrators) that action be taken with
respect thereto, whereupon the holder of such Restricted Securities shall be
entitled to transfer such Restricted Securities in

                                       4.
<PAGE>
 
accordance with the terms of the notice delivered by the holder to the Company.
Each certificate evidencing the Restricted Securities transferred as above
provided shall bear the appropriate restrictive legend set forth in Section 4(b)
above.

          5.   Adjustment of Purchase Price and Number of Shares of Common
               -----------------------------------------------------------
Stock.  The number and kind of securities purchasable upon the exercise of this
Warrant and the Warrant Price shall be subject to adjustment from time to time
upon the happening of certain events, as follows:

          (a) Consolidation, Merger, Reorganization, Etc.  If the Company at any
              -------------------------------------------                       
time while this Warrant remains outstanding and unexpired shall consolidate with
or merge into any other corporation, reorganize or reclassify, or in any manner
change the securities then purchasable upon the exercise of this Warrant, then
upon consummation thereof this Warrant shall thereafter represent the right of
Warrantholder to receive, to the extent this Warrant is exercisable as provided
above in Section 1, in lieu of shares of Common Stock, the cash or such number
of securities to which Warrantholder would have been entitled upon consummation
thereof if Warrantholder had exercised this Warrant immediately prior thereto.
Upon any such event, an appropriate adjustment shall also be made to the Warrant
Price, if necessary in the good faith judgment of the Board of Directors of the
Company, to preserve the economic benefit intended to be conferred upon
Warrantholder in accordance with its terms.

          (b) Subdivision or Combination of Shares; Dividends and Distribution
              ----------------------------------------------------------------
of Common Stock.  If the Company at any time shall subdivide or combine its
---------------                                                            
Common Stock, or take a record of the holders of its Common Stock for the
purpose of entitling them to receive without payment a dividend payable in, or
other distribution of, Common Stock or other securities, then the number of
shares of Common Stock purchasable hereunder shall be adjusted to that number
determined by multiplying the number of shares purchasable upon the exercise of
this Warrant immediately prior to such adjustment by a fraction (i) the
numerator of which shall be the total number of shares of Common Stock
outstanding immediately after such subdivision, combination, dividend or
distribution, and (ii) the denominator of which shall be the total number of
shares of Common Stock outstanding immediately prior to such subdivision,
combination, dividend or distribution.  Additionally, the Warrant Price shall be
adjusted to that price determined by multiplying the Warrant Price in effect
immediately prior to such subdivision, combination, dividend or distribution by
a fraction (x) the numerator of which shall be the total number of shares of
Common Stock outstanding immediately prior to such subdivision, combination,
dividend or distribution, and (y) the denominator of which shall be the total
number of shares of Common Stock outstanding immediately after such subdivision,
combination, dividend or distribution.

          (c) When any adjustment is required to be made in the Warrant Price,
either initially or as adjusted hereunder, the Company shall forthwith determine
the

                                       5.
<PAGE>
 
new Warrant Price and shall (i) prepare and retain on file a statement
describing in reasonable detail the method used in arriving at the new Warrant
Price; and (ii) cause a copy of such statement to be mailed to Warrantholder as
of a date within ten (10) days after the date when the circumstances giving rise
to the adjustment occurred.

          6.   Fractional Shares.  No fractional shares of Common Stock will be
               -----------------                                               
issued in connection with any exercise hereunder but in lieu of such fractional
shares, the Company shall make a cash payment therefor upon the basis of the
fair market value of the Common Stock on the date of such exercise.

          7.   Registration Rights.  The Warrant Shares shall have registration
               -------------------                                             
rights provided for in the Note Purchase Agreement.

          8.   Governing Law.  This Warrant shall be construed and enforced in
               -------------                                                  
accordance with, and the rights of the parties shall be governed by, the laws of
the State of California.

          9.   Expiration of Warrant.  This Warrant shall terminate and expire
               ---------------------                                          
and shall no longer be exercisable on or after December 16, 2001.


          IN WITNESS WHEREOF, this Warrant has been duly executed and issued by
a duly authorized officer of the Company as of this 16th day of December, 1996.


                         PLASMA & MATERIALS TECHNOLOGIES, INC.,
                         a California corporation



                         By:  /s/ John W. LaValle
                              _______________________________________
                              John W. LaValle
                              Vice President, Chief Financial Officer
                              and Secretary

                                       6.
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                              FORM OF SUBSCRIPTION
                              --------------------

                  (To be signed only upon exercise of Warrant)


To the Company:

          The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder, __________________________ (______) of the number of 
shares of Common Stock purchasable under this Warrant and herewith makes payment
of ____________ Dollars ($______) therefor, and requests that a certificate(s)
for such shares be issued in the name of, and delivered to, ___________________,
whose address is ____________________________________________________________.

          The undersigned represents that it is acquiring such shares of Common
Stock for its own account for investment purposes only and not with a view to or
for sale in connection with any distribution thereof.



DATED:___________                   __________________________________________
                                    (Signature must conform in all respects to
                                    name of holder as specified on the face of
                                    the Warrant)

 
                                    _________________________________________


                                    _________________________________________
                                    (Address)

                                       7.